OCT 21, 2021 / Technology Forefront

4K, 8K, Full HD – What’s the difference?

As I’m writing this, the Consumer Electronics Show that would usually take place in Las Vegas is instead being staged entirely online, due to the ongoing pandemic issues. CES has for the longest time been the place where big consumer electronics companies show off their latest TV innovations, and while it’s not debuting this year, there’s a whole slew of very impressive 8K TVs on show. Or, on virtual show, but you’ve got to do what the times permit, I guess.

Over time we’ve seen TV (and for that matter PC monitor) technology improve in leaps and bounds. Old school CRT TVs managed resolution a little differently, but once we shifted into flat panels, it got a little easier to compare TV resolution types.. as long as you understood what you were looking at.

In TV terms, you’re mostly going to be picking between 4K and 8K TVs this year, although there are still a few, mostly much smaller TVs on the market that don’t even go that far. That’s the domain of either HD (720p) or Full HD (1080p) screens.

Now, if you’re a little lost already, that’s OK, because it’s not as hard as you might think. When we talk about resolution on any screen, you’re numbering the pixels — those are the individual “dots” that make up each image — first horizontally and then vertically. At a very basic level, the larger the pixel number within a screen, the finer detail you can display, because you can present an image with a lot more difference between each pixel. If you think about it like old school LEGO bricks, think about the difference between building out a picture from single-stud standard LEGO bricks… or trying to do the same thing in the same space with much larger infant’s DUPLO bricks instead.

So for old-school CRTs, the effective resolution (more or less) was at best just around 720×480 pixels. That’s what’s also called “standard” definition, although it’s becoming much less common and certainly not desirable for most folks. Stepping up, you have 720p (the p is a discussion for another column), with 1280×720 pixels in a frame, also known as HD (“High Definition). HD’s bigger contemporary brother is Full HD, or 1080p, with 1920×1080 pixels to use. The step up from that — and the most common TV type available right now — is 4K, with 3840×2160 pixels.

That’s a big step up as you can imagine, and there are — many years after the first 4K TVs went on sale in Australia — a fair number of 4K video sources to watch, including many of the most popular streaming services if you’re on the right tier and have the bandwidth to handle it.

8K ups the ante to 7,680×4,320 pixels, so at a pure technical and numbers level, it’s the best in terms of the types of pictures it may be able to present. I say may there, because right now, there’s basically no actual native 8K content out there for you to enjoy at any substantial level. That’s the exact same story as 4K TVs had a few years ago, so what the TV makers are instead promoting around 8K is its ability to “upscale” existing content for smoother pictures while we wait for more 8K content to be available.

This can be very effective, because while there’s a number of quite high-priced 8K TVs to pick from, what’s also been developed in the past few years is more work around artificial intelligence to better sharpen and improve lower quality images into ones that are more aesthetically pleasing.

So for example at this year’s CES, Sony’s debuting a new AI processor in its 8K TVs that it says will analyse the images being displayed, upscale them but also process them to mimic the way our eyes focus on dominant action in the screen we’re watching. The end result — according to Sony, anyway — is that they’ll be even more lifelike. Not surprisingly, competitors such as Samsung, LG and Panasonic have broadly similar claims around their own 8K panels as well.

This kind of image improvement itself also isn’t new – even if you opt for a 4K or Full HD TV, there’s some kind of image scaler and interpreter working behind the scenes to improve images, which is part of the reason why you can get better images from a quality TV with a good scaler than a bargain basement one, even if on paper they’ve got the same resolution.

So do you need an 8K TV right away if your budget permits? Not yet, I’d say. 4K panels used to be the price of small family cars, but they’re now far more affordable from a range of brands and matched nicely with content that can actually take advantage of all those pixels. 8K may well get there in time, although given the shift to streaming video, we’ll all need reasonably good home broadband to go with it to make the most of it.

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Alex Kidman
Tech Journalist